A taxonomy of hindering events that have a negative impact on the group therapy process is identified in this analogue study, A total of 40 critical incident reports collected from various times across the lives of six different interpersonal relations groups were used for the study. Student group participants completed the critical incident reports after each session and described the most hindering event occurring in each group session: the reports were then sorted into categories by judges, and the sorted categories were combined on a proximity matrix for use in cluster analysis. Eight discrete categories of hindering events were identified: absence, discounted-misunderstood, withheld self-disclosure, member disconnection, member attack, leader actions-interventions, unwanted activity, and late group.